U.S. patent number 5,167,929 [Application Number 07/466,359] was granted by the patent office on 1992-12-01 for reaction vessel for receiving minimal quantities of fluid samples.
This patent grant is currently assigned to Walter Sarstedt Geraete und Verbrauchsmaterial fuer Medizin und. Invention is credited to Stephan Diekmann, Dagmar FLach, Dieter Korf.
United States Patent |
5,167,929 |
Korf , et al. |
December 1, 1992 |
Reaction vessel for receiving minimal quantities of fluid
samples
Abstract
In accordance with the invention, a method for executing
reactions at temperatures exceeding 50.degree. C. is disclosed
using minimal quantities of fluid samples. The method uses a
reaction vessel which minimizes the containment space for the fluid
sample. The reaction vessel includes a sample-receiving tube and an
insert. The insert engages the sample-receiving tube, forming a
seal and prevents evaporation of the fluid sample during heating.
The sample-receiving tube of the method is tapered to be narrow
towards the bottom so that the insert can be easily inserted into
the sample-receiving tube from the top and provide a tight seal in
the lower extremity without increasing pressure in the reaction
chamber. Equalization between the two sides of the sealing insert
can occur as the insert is being introduced. Minimal displacement
of the insert in the axial direction of the sample-receiving tube
produces a sealing connection minimizing undesirable pressure build
up.
Inventors: |
Korf; Dieter (Winterborn,
DE), FLach; Dagmar (Gummersbach, DE),
Diekmann; Stephan (Gottingen, DE) |
Assignee: |
Walter Sarstedt Geraete und
Verbrauchsmaterial fuer Medizin und (Nuembrecht-Rommelsdorf,
DE)
|
Family
ID: |
6825755 |
Appl.
No.: |
07/466,359 |
Filed: |
April 6, 1990 |
PCT
Filed: |
July 07, 1989 |
PCT No.: |
PCT/EP89/00786 |
371
Date: |
April 06, 1990 |
102(e)
Date: |
April 06, 1990 |
PCT
Pub. No.: |
WO90/00442 |
PCT
Pub. Date: |
January 25, 1990 |
Current U.S.
Class: |
422/534; 422/916;
422/939 |
Current CPC
Class: |
B01L
3/508 (20130101); B01L 3/50825 (20130101); B01L
7/00 (20130101) |
Current International
Class: |
B01L
3/14 (20060101); B01L 3/00 (20060101); B01L
7/00 (20060101); B01L 003/00 () |
Field of
Search: |
;422/102,104
;73/863.11,863.12 ;210/787,175 ;220/410,429 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
0245994 |
|
Nov 1987 |
|
EP |
|
330179 |
|
Jul 1958 |
|
DE |
|
83/00386 |
|
Feb 1983 |
|
WO |
|
Primary Examiner: Warden; Robert J.
Assistant Examiner: Collins; Laura E.
Attorney, Agent or Firm: Townsend & Townsend
Claims
We claim:
1. A method for reacting a given volume of a fluid sample at a
temperature at which the fluid sample generates evaporation, the
method comprising the steps of providing an elongated sample tube
having an interior wall, a first, closed end, a second, open end
and a sample tube volume, placing a given volume of fluid sample
into the closed end of the tube, inserting an insert having an end
portion capable of sealing said sample tube volume wherein proper
alignment and such that a remainder of the insert projects from the
tube and moving the end portion towards the closed end of the tube,
venting a space inside the tube between the closed end and the end
portion to an exterior of the tube while moving the end portion
during the moving step until the end portion is in a position
relative to the tube at which the closed end of the tube and a
surface of the end portion proximate the closed end of the tube
define a space, establishing a fluid tight, circumferential seal
between the end portion of the insert and the interior wall of the
tube when the end portion is at said position, thereafter holding
the end portion and the tube in their relative positions in which
they define said space, and reacting the fluid sample at said
temperature during the holding step, whereby an escape of
evaporation generated during the reacting step from said space is
prevented.
2. A method according to claim 1 wherein the step of venting
comprises the step of maintaining an air passage between the
insert, including the end portion thereof, and the interior wall of
the tube prior to the step of establishing the fluid-tight,
circumferential seal.
3. A method according to claim 1 including the step of closing the
open end of the tube when performing the step of establishing the
fluid-tight, circumferential seal.
4. A method according to claim 3 including the step of passing air
at least during the closing step through a passage in a lid or
between the lid and the interior wall of the tube.
5. A method according to claim 4 wherein the step of passing
comprises maintaining said passage open after the closing step has
been completed.
6. A method according to claim 5 wherein the step of establishing
the circumferential seal includes the step of forming opposing
sealing surfaces on the interior wall and the end portion which are
activated by moving the sealing surfaces against each other in an
axial direction of the tube, and including the step of exerting an
axially-oriented force against the circumferential seal to increase
the sealing effect established thereby.
7. A method according to claim 6 wherein the step of exerting
comprises the step of exerting the axially-oriented force on the
end portion with the lid for the tube connected with the end
portion.
Description
BACKGROUND OF THE INVENTION
The invention relates to a reaction vessel for receiving minimal
quantities of fluid samples.
In particular, molecularbiological work often calls for reactions
at temperatures exceeding 50.degree. C. (thru 100.degree. C.) as in
the high-temperature inactivation of proteins, denaturing nuclein
acids, restrictional digestion with Taq I and the like. These
reactions are usually carried out in standard reaction vessels
placed in preheated water baths or in holes drilled heated metal
blocks. The volumes of the reaction solutions are normally in the
range 10 and 50 .mu.l, the volumes of the reaction vessels between
1000 and 2500 .mu.l. The reaction vessels thus contain a large
excess volume, in which water evaporates from the reaction
solutions and is deposited on the inside of the cover. This
increases the concentrations in the reaction solution, sometimes to
the extent that the sample completely dries out. This is greatly
obstructive to the tests and treatments involved and can only be
avoided by special measures such as, for instance, repeated
centrifuging of the reaction vessels or coating the reaction
solution with oil.
OBJECT OF THE INVENTION
The object of the invention is to create a reaction vessel of the
aforementioned type in which the gas volume in a reaction vessel
filled with a reaction solution is reduced to such an extent that
evaporation of the reaction solution into larger spaces located
above is no longer possible, thus effectively preventing drying out
of the sample in heat treatment.
One aspect of the invention is to reduce the volume for the sample
in the reaction vessel with an insert to such an extent that the
space for evaporation above the sample is configured as small as
possible to accordingly limitate evaporation of the fluid from the
sample.
A further aspect of the invention is to configure a seal active on
all sides by arranging said insert as tight as possible above the
sample located in the sample-receiving tube so that the remaining
volume above the sealed off area is isolated gas-tight from the
actual reaction chamber in which the sample is located. In this way
any resulting vapor is restricted to the resulting, comparitively
small reaction chamber.
A substantial problem is posed by configuring the seal between the
insert and the sample-receiving tube so that when the insert is
pushed into the sample-receiving tube little or no pressure is
built up in the reaction chamber. This is important, for one thing,
because otherwise pushing the insert into the sample-receiving tube
is only possible by considerable exertion, and, for another thing,
buildup of pressure in the reaction chamber could be detrimental to
the sample or to the tests to be carried out.
To permit isolating a relatively small reaction chamber in the area
of the lower extremity of the sample-receiving tube without any
tangible pressure build-up in the reaction chamber when pushing the
insert into the sample-receiving tube a seal is formed only after
the insert is at its terminal position.
Since the cross-section of the sample-receiving tube is larger
above the sealing area in the lower extremity than at this
extremity, the insert can be pushed into the sample-receiving tube
from the top by its sealing lower extremity or by the sealing
element provided at its lower extremity without causing pressure to
build up, because a gap permitting pressure equalization remains
between the periphery of the sealing area or sealing element and
the internal wall of the sample-receiving tube. It is not until the
sealing area or the sealing element comes into contact with the
area of the reduced cross-section that the sealing connection is
momentarily produced, i.e. with minimal displacement of the insert
in the axial direction. Thus, there is practically no build-up of
pressure within the reaction chamber. Whilst the insert may be
formed very voluminous which is particularly useful in the
embodiment having no seal at the lower extremity of the insert, an
embodiment employing a relatively thin rod is preferred because
here very little material is required for the insert, it merely
serving as a carrier and pressure transfer element for the sealing
element provided at its lower extremity, said sealing element
having sealing contact with the interior wall of the
sample-receiving tube.
By releasably attaching the insert to the lid, the separate
reaction vessel can be used either with or without insert, as
required.
The insert can also be replaced so that, for example, inserts of
differing length and with differing sealing elements at the lower
extremity can be used, with which reaction chambers of differing
size can be separated from the remaining volume.
Particularly when sealing the reaction chamber in the area of the
lower extremity of the insert, venting of the lid is useful to
prevent any build-up of pressure in the remaining volume.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described by way of example with
reference to the following Figures, wherein:
FIG. 1 is vertical, longitudinal section through the center of a
reaction vessel according to a first embodiment of the
invention,
FIG. 2 is a corresponding section through the lower extremity of a
reaction vessel according to the invention featuring a slightly
different configuration of the seal,
FIG. 3 is a section, similar to FIG. 2, of an embodiment operating
with a graduated annular seal,
FIG. 4 is a section, similar to FIG. 1, of an embodiment of the
reaction vessel featuring a rod-type insert, and
FIG. 5 is a section through the lower extremity of a reaction
vessel according to FIG. 4 showing a different embodiment of the
sealing elements .
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
According to FIG. 1 sample-receiving tube 11 having a circular
cross-section features above a rounded tip 24 a conical section
11"" extending upwards, followed by a relatively short cylindrical
section 11"', topped by a short extension section 11" and completed
by a top cylindrical section 11' which is relatively long and has
the largest diameter relative to the other sections.
At the top of the exterior wall of the sample-receiving tube 11a
male thread 26 designed to mate with the female thread 27 of the
screw-on lid 12 is provided. On its inside the lid 12 has a
circular-cylindrical recess 28 which is open towards the bottom,
located concentrically to the centerline 23 and in which a
hollow-cylindrical insert 14 is inserted from underneath as a
sliding fit, or better, as a seized fit. Basically the insert 14
could just as well be secured in the recess 28 also by using a
suitable fastener such as an adhesive, for example. However, the
insert 14 is preferably provided for withdrawing when the lid 12 is
unscrewed, thus facilitated replacement.
The circumferential flange 29 forming the recess 28 features a
radially outwards directed slight spacing 30 from the interior wall
15 of the sample receiving tube 11 so that between the top end of
the wall 31 and a bottom annular wall 32 of lid 12 when screwed
fully in place a clearance 33 remains which borders on a side vent
opening 25 in the threaded circumferential edge 34 of the lid 12.
In this way pressure compensation is possible between the interior
space 13 of the sample-receiving tube 11 and atmosphere.
A hollow cylindrical insert 14 has a slightly smaller outer
diameter than the circular-cylindrical section 11"' and changes at
its lower extremity into a extremity section 20 which is slightly
conical in taper downwards, at the lower extremity of which the
insert 14 is closed off by a bottom wall 17.
The conical extremity section 20 has a seal contact 35 with the
interior wall 15 of the sample-receiving tube 11 within the section
11"" when lid 12 is screwed in place as shown in FIG. 1 , said
interior wall 15 also being tapered downwards in this section. In
this way the extremity section 20 together with the floor wall 17
at the lower extremity of the sample-receiving tube 11 separates a
reaction chamber 19 in which a sample 18 is filled, which is to be
exposed to heat treatment by placing the sample-receiving tube 11
in a heating apparatus.
It is assumed that in the reaction chamber 19 a quantity of approx.
100 .mu.l of sample is introduced. This quantity of sample almost
fills the reaction chamber 19 completely so that when heat is
applied the resulting vapor is forced to remain practically
completely within the sample 18 thus preventing it from drying
out.
Should only minor quantities of the sample 18--for instance only 50
.mu.l--require treatment, the insert 14 could be replaced by a
somewhat longer and more tapered insert 14 as indicated in FIG. 1
by the dashed line. In this way a much smaller reaction chamber 19'
could be separated from the overall internal volume of the
sample-receiving tube 11.
Due to the insert 14 being replaceable one-and-the-same lid 12
could be furnished with inserts 14 of differing length for
separating reaction chambers of differing volume.
On the outer circumference of the screw cap 12 a fluted surface 21
is provided to facilitate unscrewing and screwing into place. A
further fluted surface 36 is provided on the outer circumference of
the top section 11' of the sample-receiving tube 11 to present
added resistance for the other hand too, when unscrewing.
Functioning of the reaction vessel as described above is as
follows:
With the lid 12 unscrewed and the insert 14 removed the reaction
vessel first receives the sample 18 in the desired quantity in the
sample-receiving tube 11. Then, depending on the quantity of sample
filled, an insert 14 of suitable length is selected and inserted
from underneath into the screw cap 12. The insert 14 is then
introduced into the sample-receiving tube 11 so that the lid 12 can
then be screwed into place on the male thread 26, during which the
lid 12 must have adequate freedom of movement in axial direction so
that the conical extremity section 20 of the insert 14 contacts the
internal wall of the conical section (or part) 11"" of the
sample-receiving tube 11 and by turning the lid 12 further in the
closing direction sufficient axial force can be produced in the
direction of the arrow via the underside 37 of the lid 12 and the
top edge 38 of the insert 14 to create the seal 35.
As soon as the seal 35 is produced a certain residual clearance
should remain at 33.
In a top recess 39 of the lid 12 a marking label 40 is
inserted.
In the embodiment as shown in FIG. 2 contact is made not by the
complete bottom conical extremity section 20 of insert 14 with the
conical internal wall of section 11"" but merely by a lip 20'
provided in the circumference of the bottom wall 17.
Since there is a distinct space between both the extremity section
20 and the circumferential lip 20' and the internal wall 15 when
the insert 14 is introduced from above until it comes into contact
with said internal wall 15, the reaction chamber 19 can be vented
immediately prior to the seal 35 is produced thus preventing a
substantial pressure build-up in the reaction chamber 19 when
producing the seal 35.
In the embodiment as depicted in FIG. 3 an annular step 22 is
provided at the bottom extremity of the circular-cylindrical sector
11"' projecting inwards which acts together with the conical
extremity section 20 of the insert 14 in a stuffing effect, by
means of which too, the reaction chamber 19 can be separated from
the remaining volume located above gas-tight.
In all embodiment examples the reference numbers refer to
corresponding components.
The embodiment example as shown in FIG. 4 differs from that of FIG.
1 in that instead of the hollow cylindrical insert 14 a relatively
thin, rod-shaped insert 14' of solid material is provided, having
at its bottom extremity a sealing plate 17' which produces a seal
contact 35 with the interior wall of the conical section 11"" when
the lid 12 is screwed into place. The rod-shaped insert 14' can
also be separated from the lid 12 when withdrawn from the latter
and, for example, be replaced by a longer or shorter insert 14'.
Whilst in the embodiment example according to FIG. 1 venting is
provided by a lateral borehole 25 in the lid 12, the embodiment
example according to FIG. 4 a groove 25' is machined in the female
thread 26, said groove providing venting of the internal space 13
via the clearance 33 and the circumferential gap 30.
Otherwise, the function is the same as in the embodiment as shown
in FIG. 1. In FIG. 5 an annular step 22 can be provided--also in
conjunction with a rod-shaped insert 14'--at the bottom extremity
of the circular cylindrical sector 11"', said step acting together
with the plug 20" secured to the bottom extremity of said
rod-shaped insert 14'.
* * * * *